Test strip analysis apparatus of this kind are used, for example, in a doctor's practice, in hospitals or medical laboratories where blood or urine are routinely inspected using test strips, and where therefore a large number of test strips must be analyzed. An advantage of a test strip analysis apparatus of the above-mentioned type is that a test strip may be inserted directly after wetting with the liquid to be inspected without requiring the lab technician to wait for the reaction period of the respective test strip to elapse. When a large number of strips must be analyzed this would indeed be a nuisance. In an analysis apparatus of this type, the reaction period is bridged by transport of the wetted test strip from the insertion station to the optical measuring unit.
In an analysis apparatus of the above-mentioned type the transport device usually is a conveyor or the like which extends between insertion station and optical measuring unit and on which the test strips, arranged thereon in a direction transverse to the transport direction, are transported. Between the insertion of two test strips at the insertion station one must wait at least till the measuring period is over that is required for measuring the test strip with the measuring unit. Since the measuring period is typically only a fraction of the test strip's reaction period a large number of test strips are present on the conveyor at the same time, namely as many test strips as measuring periods fit into the reaction period when the capacity of the analysis apparatus is optimally used.
Since a test strip analysis apparatus of this type should, however, be as compact as possible, the length of the conveyor is limited. Consequently, the test strips are very close to one another when the apparatus capacity is fully used and the measuring period is short. Thus, even when the measuring period is indefinitely short the maximum frequency at which the test strips may be placed onto the conveyor cannot be increased at will because, given the limited length of the conveyor, the strips successively placed onto the conveyor would be too close to one another. There would be the risk of two adjacent test strips contacting one another or lying crosswise because it is not always possible to manually place the test strips onto the conveyor such that they are exactly parallel to one another. Accordingly, in order to prevent successively loaded test strips from contacting one another they must be placed onto the conveyor with a certain minimum spacing. In view of the limited length of the conveyor and the fixed transport time (namely the reaction period), this constitutes a further limitation of insertion frequency.
In practical use, however, even the insertion frequency which is theoretically possible cannot be achieved with conventional test strip analysis apparatus. This is due to the fact that, even if a lab technician were capable of preparing the test strips on average at that speed at which they can at best be inserted into the analysis apparatus, the time for preparing the test strips is of course subject to variations. In case the lab technician has prepared two strips in extremely short time one after the other, he cannot insert them as closely behind one another as he wishes because the strips would come too close on the conveyor and would reach the measuring unit following one another too rapidly. Thus, the time gained during preparation of a first strip cannot compensate the time lost during slower preparation of a following strip, because the lab technician is forced to spend the time saved during preparation of the first strip waiting for the apparatus to be ready to receive this strip. On the whole, in practical use the inflexibility regarding the time of test strip insertion leads to a decrease of performance of conventional test strip analysis apparatus.
Moreover, operation of an apparatus of this type is very uncomfortable because the lab technician must concentrate on inserting the test strip at the optimum time if he wants the make full use of the apparatus' capacity.